Sumoylation: Protein Modifications in Cancer Progression

Cancer is a mystery, an example of normal processes spiraling out of control, as cells divide and multiply and spread, often to devastating results.

Samaneh Karami, a Ph.D. student in biology, studies the cellular processes involved in breast cancer progression.According to the National Cancer Institute, approximately one out of every eight women will be diagnosed with breast cancer during her lifetime, with an estimated 40,000 deaths from breast cancer in 2017 alone.

“Cancer is so complicated,” said Samaneh Karami, a Ph.D. student in cell and molecular biology at the University of Houston’s Center for Nuclear Receptors and Cell Signaling. For her research, she studies the cellular processes involved in breast cancer progression. “I wanted to be involved in helping understand cancer.”

The Role of Protein Modifications in Cancer Progression

Karami studies how different protein modifications, when mis-regulated, can drive the progression of cancer. Her research is conducted under the guidance of Tasneem Bawa-Khalfe, assistant professor of biology and biochemistry in the College of Natural Sciences and Mathematics.

“Samaneh has done exceptionally well,” said Bawa-Khalfe. “It is very hard for a graduate student to publish within the first few years in graduate school. The fact that she published a first-author manuscript within her first 2.5 years is a phenomenal feat.”

The SUMO Protein: Affects Protein Function

Karami’s research focuses on a process known as sumoylation, which is used to regulate a variety of cell processes, such as where a protein is localized within a cell, whether or not genes get turned on or off, and how DNA gets repaired.

Sumoylation works by adding a SUMO protein to another protein. Even if the SUMO protein is quickly removed again, called desumoylation, this brief addition can change a protein’s function.

Imbalance in Sumoylation Levels Associated with Cancer Progression

Balance between sumoylation and desumoylation of proteins is required for normal cell physiology. “In many cancers, there is an imbalance in sumoylation levels,” Karami said. “In breast cancer, there is generally a high level of sumoylation.”

In Karami’s research, she focuses on the way sumoylation affects the expression of genes that promote the progression of cancer. That involves focusing on a protein, called SENP7, which removes SUMO, and how that translates to some of the changes linked to cancer progression.

Karami is interested in some of the key changes that will cause an epithelial cell, which is tightly linked with other epithelial cells, to detach and start migrating through the body. This transition, formally called an epithelial-to-mesenchymal transition, is one of the early hallmarks of cancer progression.

Karami is currently testing out SENP7’s function in mice, seeing how mis-regulation is linked to cancer progression.

“You have to be really passionate about your research,” Karami said. “It takes a long time to do experiments, and a long time to analyze data. Sometimes you just have to test, and test again.”

Juggling Research, Teaching and Family

Karami, who is juggling research, teaching, and family life, has learned a lot as a graduate student.

“You have to be really organized,” Karami said. “In the beginning of graduate school, no one can juggle all this, but eventually you learn to multitask, you learn to write abstracts, run experiments, attend seminars and teach. It’s a good experience for learning more and being more productive.”